In the last few decades, the market for low power automotive electronic devices has grown by orders of magnitude, fueled by the use of communication, sensing, storage, computing devices and increased connectivity and data transfer in cars and other portable devices. Furthermore, circuit fabrication improvements, as well as advances in circuit integration and other aspects have made electronic equipment smaller, cheaper, and more reliable. Automotive electronic circuits associated with communication, sensing, storage and computing devices as well as other portable electronic devices can operate in idle mode where zero or little power is consumed to save battery power. Meanwhile these circuits should exit idle mode correctly by a wakeup signal.